Filter For A Smoking Article

ABSTRACT

The invention provides a filter element for a smoking article. The filter element comprisesa plug of filter material, and a tobacco thread, wherein the tobacco thread extends substantially longitudinally through the plug of filter material. The filter element can be used in a variety of smoking articles.

The present invention relates to filters for smoking articles.

It is well known that filtration of smoke in a smoking article, such asa cigarette may affect the taste and flavour characteristics of aproduct when smoked. Filters commonly include adsorbent materials, suchas activated carbon, to reduce certain components of the smoke duringsmoking. However, activated carbon in a filter can adversely affect thetaste and/or flavour characteristics of a cigarette.

Therefore, in a first aspect, there is provided a filter element for asmoking article, the filter element comprising a plug of filtermaterial, and a tobacco thread, wherein the tobacco thread extendssubstantially longitudinally through the plug of filter material.

The inventors have found that the provision of the substantiallylongitudinal tobacco thread significantly improves the flavour of smoke(which comprises gas and particulate matter) that is inhaled by asmoker.

Preferably, the tobacco thread extends substantially longitudinallybetween mutually opposing end faces of the plug of filter material.Preferably, the tobacco thread extends in a direction which issubstantially parallel to a side face of the plug of filter material,which side face is preferably substantially perpendicular to one or bothend faces. Preferably, the tobacco thread extends through an innerportion of, and is surrounded by, the filter material. Preferably, thetobacco thread extends through substantially the centre of the plug offilter material.

Advantageously, the tobacco thread is disposed in close proximity withthe path of the gaseous flow as it moves through the filter element, andis therefore able to affect various characteristics of the gaseous flowbefore the flow reaches the smoker's mouth. Furthermore, because thetobacco thread is disposed substantially longitudinally within the plugof filter material, it does not adversely affect the direction or rateof gaseous flow, and so the smoker does not detect a significantdifference in the resistance to draw therethrough.

The tobacco thread may comprise shredded tobacco, powdered tobacco,reconstituted tobacco and/or cut tobacco. However, preferably thetobacco thread comprises tobacco fibres and/or tobacco sheet. Thetobacco thread may be prepared using technology known in the art. By wayof example only, a slurry comprising tobacco particles (e.g. tobaccodust and/or tobacco stems), and preferably a suitable binding agent, maybe prepared. The slurry may be spread on to a support surface, such as aconveyer, to thereby form a wet tobacco sheet. The wet sheet may then beheated, for example, by an oven, such that the slurry dries, therebyforming a tobacco sheet. The tobacco sheet may then be cut to form thethread having appropriate dimensions.

The tobacco thread may be between about 0.2 mm and 5 mm in diameter, andis preferably between about 0.4 mm and 3 mm in diameter.

Once prepared, the tobacco thread may then be encased by filter materialto form the filter element of the first aspect. The plug of filtermaterial may comprise any suitable filter media, which will be known tothe skilled technician. A preferred filter material comprises celluloseacetate. The diameter of the plug of filter material may be betweenabout 5 mm and 15 mm, preferably between 6 mm and 12 mm, more preferablybetween 7 mm and 11 mm, and most preferably between 8 mm and 10 mm. Thediameter of the plug may be between 5 and 10 mm.

Preferably, the ratio of the diameter of the plug of filter material tothe diameter of the tobacco thread is between 2:1 and 25:1, and is morepreferably between 4:1 and 10:1.

The filter element may comprise a flavourant. In embodiments where aflavourant is used, the flavourant may be incorporated in the plug offilter material. However, preferably the flavourant is incorporated inthe tobacco thread. Once formed, the thread may be dipped into a vesselcontaining the flavourant. However, preferably the flavourant isincluded in the slurry from which the thread is prepared.

It will be appreciated that the filter element according to the firstaspect may be used in the manufacture of a filter, for use in a smokingarticle.

Hence, according to a second aspect of the invention, there is provideda filter for a smoking article, the filter comprising a filter elementaccording to the first aspect.

The filter of the second aspect may comprise a plurality of filterelements according to the first aspect, in which a tobacco threadextends through a plug of filter material. For example, the filter maycomprise 2, 3, 4, 5 or more filter elements of the first aspect, inwhich adjacent filter elements may either be connected to each other, orwhich elements may be separated from each other by other filter elements(which may not be in accordance with the first aspect).

Hence, the filter may comprise a plurality of filter elements, at leastone of which is a filter element according to the first aspect of theinvention. For example, it is envisaged that, in one embodiment, inaddition to comprising one or more filter elements according to thefirst aspect (ie. containing the tobacco thread), the filter of thesecond aspect may also comprise an adsorbent filter element, whichelement comprises an adsorbent material. The adsorbent filter element isprovided to adsorb and, hence, reduce certain components of the smokeduring smoking. The adsorbent filter element may comprise a plug offilter material in which the adsorbent material is dispersed. The filtermaterial may be cellulose acetate. A preferred adsorbent material isactivated carbon. The activated carbon may be in the form of granularactivated carbon, which is preferably distributed substantiallythroughout the volume of the plug of filter material. Preferably, theadsorbent filter element does not include a tobacco thread.

In another embodiment, in addition to comprising one or more filterelements according to the first aspect (ie. containing the tobaccothread), the filter of the second aspect may also comprise a filterelement, which comprises filter material (such as, cellulose acetate),and which does not include a tobacco thread or adsorbent material.

The filter may comprise at least two, and preferably at least threefilter elements, provided that at least one filter element is inaccordance with the first aspect. Preferably, the filter comprises afilter element according to the first aspect, an adsorbent filterelement comprising adsorbent, and a filter element, which does notinclude adsorbent or a tobacco thread. Preferably, multiple filterelements are arranged longitudinally of one another with the end face ofone filter element abutting the end face of an adjacent filter element.It is preferred that the filter elements have substantially similardiameters. It should be appreciated that the various filter elements maybe in any order in the filter, as illustrated in FIGS. 3 and 4.

The filter element of the first aspect, or the filter of the secondaspect, may be incorporated into a smoking article.

Hence, according to a third aspect of the invention, there is provided asmoking article comprising a filter element according to the firstaspect, or a filter according to the second aspect.

The smoking article preferably comprises a section of smokeablematerial, such as tobacco. As used herein, the term “smoking article”includes smokeable products such as cigarettes, cigars and cigarilloswhether based on tobacco, tobacco derivatives, expanded tobacco,reconstituted tobacco or tobacco substitutes and also heat-not-burnproducts.

The section of smokeable material and the filter may be attached bytipping paper.

According to a fourth aspect of the invention, there is provided amethod of manufacturing a filter element for a smoking article, themethod comprising providing a tobacco thread through a plug of filtermaterial, wherein the tobacco thread extends substantiallylongitudinally through the plug of filter material.

The method preferably comprises a step of introducing the tobacco threadinto substantially the centre of the filter material. The method maycomprise using guide means to guide the tobacco thread as a tow offilter material is formed therearound. The guide means may comprise aguide tube through which the thread is entrained. As the thread exitsthe guide means, it is preferably surrounded by filter material.

All of the features described herein (including any accompanying claims,abstract and drawings), and/or all of the steps of any method or processso disclosed, may be combined with any of the above aspects in anycombination, except combinations where at least some of such featuresand/or steps are mutually exclusive.

For a better understanding of the invention, and to show how embodimentsof the same may be carried into effect, reference will now be made, byway of example, to the accompanying Figures, in which:

FIG. 1 shows a perspective view of a smoking article, including a rod ofsmokeable material, a filter in accordance with the invention, andtipping paper attaching the rod and filter together;

FIG. 2 shows a cross-sectional side view of a first embodiment of thefilter according to the invention;

FIG. 3 shows a cross-sectional side view of a second embodiment of thefilter; and

FIG. 4 shows a cross-sectional side view of a third embodiment of thefilter.

Referring to FIG. 1, there is shown a smoking article 2, in the form ofa cigarette, which includes a filter 4 in accordance with the invention.Even though the Figures show the smoking article 2 as a cigarette, itshould be appreciated that the smoking article 2 may take other forms,such as cigars and cigarillos etc, which may also include the filter 4according to the invention. Referring to FIG. 1, the smoking article 2comprises a generally cylindrical paper-wrapped rod 6 of smokeablematerial, such as tobacco, which is co-axially attached to the filter 4by tipping paper 8, which is glued around one end of the rod 6 and thefilter 4.

Referring to FIG. 2, there is shown a first embodiment of the filter 4attached to the rod of tobacco 6. In this embodiment, the filter 4 ismade up of a single, filter element 12 about 27 mm in length, whichconsists of a continuous plug of filter material 20 (for example,cellulose acetate) having a diameter of 9 mm. The filter element 12 hasfirst and second generally circular end faces 22, 24, and acircumferential or longitudinally extending side surface 26substantially perpendicular to the first and second end faces 22, 24. Asshown in FIG. 2, a thin tobacco thread 10 having a diameter of 0.8 mmextends between the two end faces 22, 24 through the plug of filtermaterial 20. The thread is substantially parallel with thelongitudinally extending surface 26, and extends substantially throughthe centre of the plug of filter material 20, thereby forming a core.

The thread of tobacco 10 is prepared either from tobacco fibres and/ortobacco sheet, using technology known in the art, and using materialswhich may be obtained from LTR industries, France, or from Deli-HTL,Holland. For example, a wet slurry of tobacco dust, cut tobacco stems,and a binding agent is initially prepared, and then rolled out on to astainless steel conveyer to form a wet tobacco sheet. The conveyer isfed into an oven which heats the slurry until it dries, thereby forminga band cast reconstituted tobacco sheet. For example, suitable heatingmay be at about 70-100° C. for about 6-8 minutes. The tobacco sheet isthen cut to the appropriate dimensions (0.8 mm diameter) by cutters toproduce thread 10, which may then be fed on to a reel, ready for use.Flavourant may be added to the sheet, before being formed into thethread 10. Another example for preparing the tobacco thread 10 is bytightly twisting tobacco plant fibres in a similar method to that usedfor preparing cotton.

The resultant thread 10 is approximately 0.8 mm in diameter, which isthen introduced into the centre of the filter material 20. One method ofintroducing the tobacco thread 10 in to the plug of filter material 20in the manufacture of the filter element 12 as follows. The methodinvolves entraining the tobacco thread 10 through the lumen of a guidetube having a diameter of about 1.5 mm. Simultaneously, a supply offibrous filter material 20 (e.g. cellulose acetate) is passed through aseries of blooming rollers so that it is de-crimped. A tow of de-crimpedfilter material 20 is then formed around the thread 10 as it exits theguide tube, to thereby form a continuous rod of filter material 20enclosing the thread 10. The rod may then be cut up in to sections toproduce the completed filter element 12 as shown in FIG. 2. The lengthof the filter element 12 will depend on the type of filter 4 required.For example, a standard cigarette filter 4 is about 27 mm in length. Inthe embodiment shown in FIG. 2, the whole 27 mm length of the filter 4consists of the filter element 12, such that the thread 10 extends allthe way along. However, FIGS. 3 and 4 illustrate other embodiments, inwhich the filter 4 comprises a shorter section of the filter element 12containing the thread 10 in combination with other sections, asdescribed below.

Referring to FIG. 3, there is a shown a second embodiment of the filter4 attached to the rod of tobacco 6. The filter 4 comprises a pluralityof different discrete filter elements 12, 14, 16, each of which may havea different material composition. In this embodiment, the filter 4includes three different filter elements 12, 14, 16. Each filter element12, 14, 16 is generally cylindrical in shape having substantiallyequivalent diameters. Each filter element 12, 12, 16 is wrapped by alayer of thin sheet material in the form of a wrapper known as plugwrap(not shown), which may be formed of conventional paper materials. Thefilter element 16 that is farthest from the tobacco rod 6 (and whichwill be closest to the smoker's mouth when in use) comprises a generallycylindrical tow of filter material 20, such as cellulose acetate. Thefilter material 20 provides a filter through which smoke may pass as asmoker inhales on the cigarette. The filter element 12 that is disposedadjacent element 16 contains a continuous plug of filter material 20having the tobacco thread 10 extending substantially longitudinallytherethrough. This filter element 12 is similar to that shown in FIG. 1,except that it does not extend along the entire length of the filter 4.

The third filter element 14 that is disposed between the filter element12 containing the tobacco thread 10 and the tobacco rod 6 comprises aplug of filter material 20, in which an adsorbent, such as activatedcarbon 18, has been dispersed. The activated carbon 18 may be in theform of granular activated carbon 18, which is distributed evenlythroughout the volume of the plug of cellulose acetate 20 in a“Dalmatian” style, as is known in the art, and as shown in FIG. 3.Alternatively, the activated carbon 18 may be sprinkled onto a stickyexterior surface 26 of the plug of cellulose acetate 20, or adhered tothe inner surface of plugwrap surrounding the cellulose acetate, oradhered to a cotton thread surrounded by the plug of cellulose acetate20 (not shown). The activated carbon 18 could also be held in a cavitysurrounded by the plug of cellulose acetate 20. The activated carbon 18is provided to improve the characteristics of the smoke that is inhaledby removing toxic chemicals.

Referring to FIG. 4, there is a shown a third embodiment of the filter 4attached to the tobacco rod 6. In this embodiment, the filter 4 includesthe same three filter elements 12, 14, 16 as in the second embodiment,as described above, except that the order of the elements has beenchanged. As shown in FIG. 4, the filter element 16 that is farthest fromthe tobacco rod 6 comprises filter material 20, such as celluloseacetate, as in the second embodiment. However, in the third embodiment,the filter element 12 that is disposed adjacent element 16 contains aplug of filter material 20, in which particles of activated carbon 18have been dispersed. Finally, the third filter element 12 disposedbetween element 14 and the rod of tobacco 6 contains a continuous plugof filter material 20 through which the tobacco thread 10 extends.Accordingly, the positions of filter elements 12, 14 have been swappedin the second and third embodiments.

As shown in FIGS. 3 and 4, the filter elements 12, 14, 16 are arrangedlongitudinally of one another with the end face 22, 24 of each filterelement 12, 14, 16 abutting the next. Although the three filter elements12, 14, 16 are shown in FIGS. 3 and 4 as being substantially equal inlength, it will be appreciated that they could have different lengths.For example, in FIGS. 3 and 4, the filter element 12 containing thetobacco thread 10 could be 12 mm in length, and the other elements 14,16 could be 7.5 mm each, such that the total length of the filter 4 is27 mm. In addition, it will be appreciated that the filter 4 maycomprise only the two filter elements. For example, the filter 4 maycomprise the filter element 12 containing the tobacco thread 10 (about15 mm long) and the filter element 16 containing only filter material 20(about 12 mm long), in either order. Alternatively, the filter 4 maycomprise the filter element 12 containing the tobacco thread 10 and thefilter element 14 containing activated carbon 18, in either order.

Also, the filter 4 may comprise more than three filter elements 12, 14,16. For example, the filter 4 may comprise first and second filterelements 16 composed of cellulose acetate, a third filter element 14comprising cellulose acetate and activated carbon 18, and a fourthfilter element 12 comprising the longitudinal tobacco thread 10 core, asdescribed above. It will be appreciated that the various filter elements12, 14, 16 may be arranged in the filter 4 in a variety of alternativeorders. However, in each embodiment, at least one filter element 12containing the tobacco thread 10 is included in the filter 4.

Referring to FIG. 1 once again, the filter 4 is located at a mouth-endof the smoking article 2 such that a gaseous flow, comprising smokedrawn from the rod 6 of smokeable material, moves through the filter 4before entering the mouth of a smoker. The tobacco thread 10 is locatedin one or more filter elements 12, and extends longitudinally betweenthe end faces 22, 24 of a plug of filter material 20, as described inrelation to FIG. 2. In this way, the tobacco thread 10 is disposed inclose proximity with the path of the gaseous flow as it moves throughthe filter 4, and is therefore able to affect various characteristics ofthe gaseous flow before the flow reaches the smoker's mouth.

The tobacco thread 10 may, for example, affect the overall properties ofthe gaseous flow such that the taste and flavour of the gaseous flow areimproved. One application of the tobacco thread 10 is to replace adegree of the taste and flavour characteristics of the gaseous flowwhich may be lost as the gaseous flow moves through the filter material20, or the activated carbon 18, which is known to affect the taste andflavour of tobacco smoke. The inventors have surprisingly found that thearrangement of the thin thread of tobacco 10 extending longitudinallythrough the plug of filter material 20 improves the flavour of the smokewithout compromising the flow characteristics of the smoke.

The invention also includes further modifications and variations fallingwithin the scope of the claims.

1. A filter element for a smoking article, the filter element comprisinga plug of filter material, and a tobacco thread, wherein the tobaccothread extends substantially longitudinally through the plug of filtermaterial.
 2. The filter element according to claim 1, wherein thetobacco thread extends substantially longitudinally between mutuallyopposing end faces of the plug of filter material.
 3. The filter elementaccording to claim 2, wherein the tobacco thread extends in a directionwhich is substantially parallel to a side face of the plug of filtermaterial, which side face is substantially perpendicular to one or bothend faces.
 4. The filter element according to claim 1, wherein thetobacco thread extends through an inner portion of, and is surroundedby, the filter material.
 5. The filter element according to claim 1,wherein the tobacco thread extends through substantially the center ofthe plug of filter material.
 6. The filter element according to claim 1,wherein the tobacco thread comprises shredded tobacco, powdered tobacco,reconstituted tobacco or cut tobacco.
 7. The filter element according toclaim 1, wherein the tobacco thread comprises tobacco fibers or tobaccosheet.
 8. The filter element according to claim 1, wherein the tobaccothread is between 0.2 mm and 5 mm in diameter.
 9. The filter elementaccording to claim 1, wherein the plug of filter material comprisescellulose acetate.
 10. The filter element according to claim 1, whereinthe diameter of the plug of filter material is between 5 mm and 15 mm.11. The filter element according to claim 1, wherein the filter elementcomprises a flavourant.
 12. A filter for the smoking article, the filtercomprising the filter element according to claim
 1. 13. The filteraccording to claim 12, wherein the filter comprises a plurality offilter elements, at least one of which is a filter element comprisingthe plug of filter material, and the tobacco thread, wherein the tobaccothread extends substantially longitudinally through the plug of filtermaterial.
 14. The filter according to claim 12, wherein the filtercomprises an adsorbent filter element, which element comprises anadsorbent material.
 15. The filter according to claim 14, wherein theadsorbent material is activated carbon.
 16. The filter according toclaim 12, wherein the filter comprises the filter element, whichcomprises filter material (such as, cellulose acetate), and which doesnot include a tobacco thread or adsorbent material.
 17. A smokingarticle comprising a filter element according to claim
 1. 18. A methodof manufacturing a filter element for a smoking article, the methodcomprising providing a tobacco thread through a plug of filter material,wherein the tobacco thread extends substantially longitudinally throughthe plug of filter material.
 19. The method according to claim 18,wherein the method comprises introducing the tobacco thread intosubstantially the center of the filter material.
 20. The methodaccording to claim 18, wherein the method comprises using guide means toguide the tobacco thread as a tow of filter material is formedtherearound.
 21. The method according to claim 20, wherein the guidemeans comprises a guide tube through which the thread is entrained. 22.A smoking article comprising a filter according to claim
 12. 23. Thefilter element according to claim 1, wherein the tobacco thread isbetween 0.4 mm and 3 mm in diameter.
 24. The filter element according toclaim 1, wherein the diameter of the plug of filter material is between8 mm and 10 mm.